The present invention relates generally to a spherical retainer and, more particularly, to a method and apparatus for forming a spherical retainer in a single stroke stamping operation.
Spherical retainers used, for example, in self-aligning bearings and rod end bearings have been formed in the prior art in a single stamping operation. In the prior art, a truncated spherical bearing is initially inserted into a generally cylindrical member or sleeve with the combination bearing and sleeve being subjected to a stamping operation which conforms the sleeve to the bearing. Such formation typically seizes the truncated spherical bearings within the sleeves as they are stamped to form spherical retainers. In U.S. Pat. No. 2,724,172, the spherical retainer or outer race member is subsequently subjected to a rolling force to free the retainer from the bearing.
In U.S. Pat. No. 2,728,975, a single step stamping operation is also performed to form a retainer about a truncated spherical bearing inserted therein. To free the retainer from the bearing in the disclosed process, the bearing is initially heated above room temperature prior to the formation of the retainer.
In U.S. Pat. No. 2,892,246, a self-aligning bearing is formed in a single stamping operation wherein a truncated spherical bearing is initially inserted into a generally cylindrical member which is then stamped around the bearing to form a retainer. In the disclosed process, relative movement of stamping dies is stopped at a predetermined point by abutment of a die with a post positioned within the truncated spherical bearing such that the bearing is not seized by formation of the retainer.
Similarly, U.S. Pat. No. 4,207,659 is directed to a method for forming a bearing housing in which a semi-finished housing is assembled with the bearing and the outside of the semi-finished housing is pressed inwardly to conform the inside surface of the housing to the outside surface of the bearing on a machine press. In the disclosed process, limited force is exerted such that the bearing is not seized by formation of the housing or retainer.
More recently, retainers for truncated spherical members have been formed separate from the spherical members to permit later assembly by hand or the use of hand tools. U.S. Pat. No. 4,428,688 to John C. McGregor, Jr., the inventor herein, is directed to a spherical retainer and is hereby incorporated by reference. The McGregor retainer is constructed from a planar support member having an opening therein by outwardly bending alternating pairs of diametrically opposed lip members to opposite sides of the support member. The lip members are positioned and dimensioned such that a truncated spherical member can be inserted into the retainer opening with its center axis oriented perpendicular to the center axis of the retainer opening and rotated about an equatorial axis by hand or with a hand tool into a position in which its center axis is common with the center axis of the retainer opening. In this position, the spherical member is locked against relative axial movement by the lip members.
The McGregor retainer previously has been formed in a two step stamping operation wherein the planar support member is initially inserted into a pair of dies which forms the lip members extending to one side of the support member. The support member is then flipped and rotated such that the same pair of dies is used to form the lip members extending to the opposite side of the planar support member. While the McGregor retainer is advantageous for its simple economical unitary construction and because it permits hand or hand tool assembly, the second step of the two step process used to form the retainer tends to deform the first stamped lip members reducing the tolerances which may be achieved.
Accordingly, a spherical retainer which has all the advantages of the McGregor retainer and at the same time may be formed in a single stamping operation would be desirable for use in those applications in which closer tolerances are desirable or required.